oldworld-debian.sh

#!/bin/bash
set -e

# This script identifies the packages manually installed on your old
# Debian system that are not installed on your new Debian system.

if test "$#" -ne "2" ; then
  echo >&2 "usage: $0 /path/to/old/var/lib/dpkg /path/to/old/var/lib/apt"
  exit 1
fi

export COLUMNS=256

comm -23 \
  <( comm -23 \
    <(dpkg-query --admindir $1 -l | awk '{print $2}' | sort) \
    <(dpkg-query               -l | awk '{print $2}' | sort) \
  ) \
  <( \
    sed -n '/^$/!{;H;d;};x;/\nAuto-Installed: 1/s/^\nPackage: \([^\n]*\)\n.*/\1/p' "$2/extended_states" | sort \
  ) \
  | cat